Rarible protocol smart contracts for NFT

Architecture

These contracts are built using openzeppelin's upgradeable smart contracts. There are 2 versions of tokens:

• Rarible common contracts (ERC-721 and ERC-1155)
• Rarible user-owned contracts (ERC-721 and ERC-1155) - users deploy these contracts, only owners can mint in these

All these contracts support these features:

• lazy mint: there is mintAndTransfer function, it mints and transfers NFT to the new owner
• Rarible on-chain royalties
• multiple creators
• supports operators (who can transfer tokens on behalf of users) for the whole smart contract
• upgradeable

User-owned contracts use beacon proxies and these contracts can be updated by rarible DAO. Rarible common contracts can be upgraded too.

Minting

Minting is done using mintAndTransfer function in both (ERC-721 and ERC-1155) contracts. For ERC-721 function has following signature: mintAndTransfer(LibERC721LazyMint.Mint721Data memory data, address to)

    struct Mint721Data {
        uint tokenId;
        string tokenURI;
        address[] creators;
        LibPart.Part[] royalties;
        bytes[] signatures;
    }

• tokenId - regular ERC-721 tokenId
• tokenURI - suffix for the token uri. prefix is usually "ipfs:/"
• creators - array of addresses who considered authors of the work. Will be saved, anyone can query this info.
• royalties - array of royalties, will be saved. . Will be saved, anyone can query this info.
• signatures - array of signatures of this information. Signature should be present for every creator (only exception is when creator sends mint transaction)

For ERC-1155 function has some more arguments: mintAndTransfer(LibERC1155LazyMint.Mint1155Data memory data, address to, uint256 _amount)

    struct Mint1155Data {
        uint tokenId;
        string tokenURI;
        uint supply;
        address[] creators;
        LibPart.Part[] royalties;
        bytes[] signatures;
    }

• tokenId - ERC-1155 tokenId
• tokenURI - suffix for the token uri. prefix is usually "ipfs:/"
• supply - total supply for tokenId. can not be changed after initial mint.
• creators - array of addresses who considered authors of the work. Will be saved, anyone can query this info.
• royalties - array of royalties, will be saved. . Will be saved, anyone can query this info.
• signatures - array of signatures of this information. Signature should be present for every creator (only exception is when creator sends mint transaction)

mintAndTransfer for ERC-1155 can be called multiple times until total minted amount is not equal to supply.

Lazy minting

Function mintAndTransfer can be used for regular mint (when creator mints NFT). Or it can be used for lazy mint: when creator signs mint request data and then anyone can mint NFT.

transferFromOrMint first transfers tokens already minted, then it mints token if necessary

Smart-contract wide operator

Our smart contracts have one smart-contract wide operator (Rarible protocol Exchange contracts). This prevents users from approving transfers to our Exchange contracts. This way users save gas fees.